The present invention relates to an ultrasound image generating apparatus and particularly to an ultrasound image generating apparatus for displaying a puncture device together with a body tissue on a monitor screen.
In medical fields, ultrasound image generating apparatuses are widely used for diagnoses and examinations. An ultrasound image generating apparatus is used with an ultrasound probe. The ultrasound probe emits ultrasonic waves to a subject, whereupon the ultrasound image generating apparatus generates an ultrasonic tomographic image of the subject from an echo signal generated as the ultrasonic waves are reflected by the subject (hereinafter referred to as ultrasound image).
The ultrasound probe comprises a piezoelectric device array composed of a plurality of arrayed piezoelectric devices; the ultrasound probe emits ultrasonic waves from the piezoelectric device array to the subject and receives an echo signal from the subject. The ultrasound image generating apparatus generates an ultrasound image of the subject based on the echo signal received by the ultrasound probe and displays the generated image on the monitor.
In order to view a particular imaging target with a high definition, ultrasound image generating apparatuses use electronic focusing to align the focal point position with an imaging target position.
Electronic focusing means actuating a plurality of piezoelectric devices with a temporal difference so that the ultrasonic waves emitted from the piezoelectric devices align with each other in phase at the focal point position and likewise performing delay addition such that the echo signals received from the focal point position by the piezoelectric devices are temporally in phase. Near the focal point position, high-resolution tomographic image information can be obtained.
With ultrasound image generating apparatuses, paracentesis is performed by inserting a puncture needle into a desired site to obtain a tissue sample for definitive diagnosis. JP 2008-188178 A describe an apparatus wherein, in performing a paracentesis, a puncture guideline for performing a paracentesis is displayed on a monitor to permit changing the focal point position of electronic focusing in the array direction of the piezoelectric device array in order to acquire high-resolution tomographic image information at a target position in the focal point depth direction.